The concept of the nuclear battery has been known since the work of Philip Edwin Ohmart in 1951. Cells of this type, the most current nuclear or beta voltaic cells, consist of a tritium doped diode, a radioactive isotope of hydrogen, and use a non-thermal conversion process. This dopant emits ionizing radiation in the diode itself. The diode then produces a corresponding electrical current. The inconvenience of this technology is that it involves handling radioactive materials.
In addition, the generator of the invention is different from photovoltaic cells with a diode base in that it does not need to be exposed to the photonic radiation of the Sun, in direct light. On the contrary, it can be placed inside a craft, typically a spacecraft or aircraft, and thereby continue to be protected from mechanical projections whilst continue to produce electricity.
In the invention, the solution proposed is to use as a source of energy the natural radiative environment or any other ionizing radiative environment, and not a radioactive isotope present in the generator.
The radiative environment with a cosmic origin comes from the Sun (solar wind and eruptions) and from interstellar and intergalactic space which permanently emits very varied natural energy particles: cosmic rays. This includes the part charged mainly with protons (between 85% and 90%) and helium nuclei (between 9% and 14%), with the remainder consisting of electrons, various nucleons (atomic nuclei) as well as small quantities of light anti-matter (antiprotons and positrons). The neutral part consists of gamma rays as well as neutrinos.
The terrestrial magnetic field diverts the major part of these cosmic rays. A significant proportion of the protons and electrons are trapped around the field lines, forming a region commonly called a radiation belt. The other part, under a process of spallation from heavier nuclei present in the atmosphere, produces secondary or tertiary ionizing radiation and particles (neutrons, photons, pions, muons, electrons, alpha ions . . . ). This phenomenon is called atmospheric cascade. FIG. 1 shows such a cascade taking place at altitudes of between 35 km and 0 km from the Earth's surface.
Consequently, between the upper layer of the atmosphere and sea level, the formation of particles is variable. Nevertheless, the flow of secondary charged particles is reduced because of their interaction with the molecules present in the atmosphere. The result is a predominance of neutrons at aircraft flying altitudes.
The neutron flow present in the atmosphere varies according to latitude and altitude, and doubles at 1,500 m altitude compared with ground level. It also varies under the effects of changes in solar activity.
In addition to the natural radiative environment of cosmic origin, a component at ground level comes from the natural activity of the ground produced by radioactive substances such as uranium, thorium or potassium-40. These emit gamma and beta rays. Other environments with ionizing radiation are civil nuclear plants and the military nuclear and medical fields.